GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"26712 results found.
- EP250511a: Gemini optical counterpart observation
- EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
- EP250511a: Mephisto optical upper limits
- GRB 250512B: SVOM detection of a burst
- EP250512a: Einstein Probe detection of an X-ray transient
- EP250511a: REM optical/NIR observations
- EP250511a: Einstein Probe follow-up obsevation and refined analysis
- EP250511a: COLIBRÍ optical counterpart candidate
- EP250511a: Einstein Probe detection of an X-ray transient
- EP250508a: Gemini NIR upper limits
- GRB 250510B: Fermi GBM Observation
- GRB 250510A: Swift-XRT observations
- GRB 250509A: Fermi GBM Observation
- IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
- GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
- GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250509A: Swift-XRT refined Analysis
- GRB 250510A: SVOM possible detection of a burst
- GRB 250507A: J-band observations with WINTER
- GRB 250509A: Enhanced Swift-XRT position
- GRB 250509A: Swift detection of a burst
- GRB 250506A: NOT optical upper limits
- EP250508a: Liverpool Telescope optical upper limits
- EP250508a: follow-up observation with EP-FXT
- EP250508a: KAIT optical upper limit
- GRB 250507A: KAIT optical upper limit
- EP250508a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 250505B: SVOM/GRM observation of a short burst
- GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- GRB 250506A: GECAM detection
- EP250508a: REM optical/NIR observations
- GRB 250506A: Swift-XRT afterglow detection
- EP250508a: COLIBRÍ Optical Limit
- EP250508a: Einstein Probe detection of an X-ray transient
- GRB 250507A: Swift-XRT refined Analysis
- IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250506A: Swift/UVOT Upper Limits
- GRB 250507A: follow-up observation with EP-FXT
- EP#01709175213/IGR J19566+0326: Swift-XRT detection
- GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250507A: refined SVOM/MXT data analysis
- GRB 250507A: REM optical/NIR observations
- GRB 250507A: SVOM/VT optical upper limit
- GRB 250506A: Swift-XRT observations
- Fermi-LAT Gamma-ray Observations of IceCube-250506A
- GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
- GRB 250507A: SVOM detection of a long burst
- GRB 250506A: Mephisto optical upper limits
- GRB 250502A: Bassano Bresciano Observatory upper limit
- GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
- GRB 250506A: Xinglong 2.16m optical upper limit
- SVOM/sb25050601: EP-FXT observations
- GRB 250506A: REM optical/NIR upper limits
- GRB 250506A: Fermi GBM Observation
- GRB 250506A: Swift XRT observations and possible counterpart detection
- GRB 250506A: TRT optical observations
- GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
- GRB 250506A: SVOM detection of a burst
- GRB 250504A: Swift-XRT refined Analysis
- GRB 250504A: VLT/X-shooter upper limits
- GRB 250504A: REM optical/NIR observations
- GRB 250502A: REM optical/NIR observations
- GRB 250504A: MeerLICHT optical afterglow detection
- GRB 250504A: Fermi GBM Observation
- GRB 250504A: Enhanced Swift-XRT position
- GRB 250504A: Swift detection of a burst
- GRB 250502A: Swift/UVOT Follow up
- GRB 250502A: KAIT optical observations
- GRB 250502A: Montarrenti Observatory optical detection
- GRB 250502A: Swift-XRT afterglow detection
- GRB 250502A: NOT optical observations
- GRB 250502A: AKO Optical Afterglow Detection
- GRB 250502A: LCO optical counterpart detection
- GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
- GRB 250407A: VZLUSAT-2 detection
- Fermi-LAT Gamma-ray Observations of IceCube-250429A
- GRB 250502B: DDOTI Optical Observations
- GRB 250430A: Swift-XRT refined Analysis
- GRB 250502A: Early optical counterpart detection by LCO.
- GRB 250430A: Swift/UVOT Detection
- GRB 250502A: TRT optical afterglow confirmation
- GRB 250430A: Enhanced Swift-XRT position
- GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
- GRB 250502B: Fermi GBM Final Real-time Localization
- GRB 250502A: SVOM detection of a burst
- GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
- GRB 250430A: KAIT optical observations
- GRB 250430A / EP250430a: J-band upper limits with WINTER
- GRB 250430A: DDOTI Optical Observations
- GRB 250430A: Leavitt Observatory optical upper limit
- GRB 250430A: Bassano Bresciano Observatory upper limit
- GRB 250430A : MITSuME Akeno optical upper limits
- SVOM/sb25043004: EP-FXT observations
- EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
- IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250430A: AKO Optical Afterglow Detection
- GRB 250430A: Kanata optical upper limit
- EP 250427A: Optical counterpart detection by LCO.